Rolling contact bearings are also known as anti-friction bearing due to its low friction characteristics between ball and inner and outer rings. Rolling contact bearings are used for radial load, thrust load and combination of these both loads. Rolling contact bearings are often used due to its lower price, less maintenance cost and easy to operate.

1. PRESENTATION ON
“MODES OF FAILURE OF ROLLING
CONTACT BEARING”
BY
RAVAL KRUNAL - 160140119096
SAKHIWALA MAHIR - 160140119098
SARDHARA KISHAN - 160140199099

2. CONTENT
 Introduction to rolling contact bearing
 Failure of rolling contact bearing due to Breakage
 Failure of rolling contact bearing due to Pitting
 Failure of rolling contact bearing due to Scoring
 Failure of rolling contact bearing due to Abrasive wear
 Failure of rolling contact bearing due to Corrosive wear
 Failure of rolling contact bearing due to Cracking damage

3. INTODUCTION
• Rolling contact bearings are also known as anti-friction
bearing due to its low friction characteristics between ball and
inner and outer rings. Rolling contact bearings are used for
radial load, thrust load and combination of these both loads.
Rolling contact bearings are often used due to its lower price,
less maintenance cost and easy to operate.

4. TYPES(MODES) OF FAILURES OF
ROLLING CONTACT BEARINGS:
 Breakage or fracture
 Pitting (spalling)
 Scoring
 Abrasive wear
 Corrosive wear
 Cracking damage

5. BREAKAGE OR FRACTURE
• The inner race, outer race, rolling element or cage may fail due
to breakage.
1. The inner race or outer race may permanently deform or fracture
due to over load.
2. The rolling elements either permanently deform or get crushed due
to over load or misalignment.
3. The cage may break due to axial load or centrifugal force.
• Remedies : breakage can be avoided by :
1. maintaining the load on bearing within the limit;
2. Selecting the correct type of bearing for a given application;
3. Proper alignment between axis of shaft and housing.
4. Operating the bearing within permissible speed limits.

6. PITTING (SPALLING)
 Pitting is a surface fatigue failure due to repetitive contact
stresses. It starts when the maximum Hertz contact stress
induced on inner race, outer race or rolling elements exceeds
the surface endurance strength.
 The pitting begins as a micro-crack on the surface and
progressively develops into a big pit on the surface.
 Remedies : the pitting can be avoided by :
1. Increasing the surface hardness of rolling elements and race;
2. Maintaining the load on the bearing within the limits.

7. Four stages of pitting failure

8. SCORING
 Scoring is essentially a lubrication failure. Inadequate
lubrication along with high load and poor surface finish results
in break-down of the lubrication film and causes metal-to-
metal contact.
 The high coefficient of sliding friction resulting from
inadequate lubrication, poor surface finish, high load and high
speed results in excessive heat generation in the localised
region of metal-to-metal contact.
 This causes rapid alternate welding and tearing at high spots
which is known as stick-slip phenomenon.

9. Scoring or lubrication
failure
Remedies : the scoring can be avoided by:
1. Providing an adequate lubrication;
2. Providing the proper surface finish;
3. Maintaining the load within the limit;
4. Maintaining the speed within the limit

10. ABRASIVE WEAR
• Abrasive wear is a surface damage caused by particles trappeed between
the race and rolling element.
• These particles may be : impurities in lubricant , dirt entering the bearing
from outside or wornout particles of bearing itself. These particles scratch
the rolling elements or races.
• Remedies : the abrasive wear can be avoided by :
1. Providing the seals;
2. Increasing the surface hardness;
3. Use of high viscosity lubricating oils.

11. CORROSIVE WEAR
• Corrosive wear is due to chemical action by the improper lubricant or
sometimes it may be due to the surrounding atmosphere which may be of
corrosive nature.
• Remedies :
corrosive wear can be avoided by :
1. Using proper lubricant with proper additives;
2. Providing complete enclosure for bearing.

12. CRACKING DAMAGE
• Cracks or pieces broken off, generally at one face of the bearing.
• causes :
I. Excessive interference
II. Excessive load, shock load
III. Heat generation due to creep
IV. Poor taper angle of tapered shaft
V. Poor cylindricality of shaft
• Remedies :
I. Correct the interference
II. Check the load conditions
III. Improve the mounting method
IV. Use of appropriate shaft shape

13. Thank you